User Control Weather Fixes

Weather control was not being displayed correctly in the GUI. Once shown
on one screen, would be displayed on all screens. Weather object only
provides for five days forcast, so removed day 6 from control. Provided
for caching of images on local drive to reduce time to load and
bandwidth usage. Refactored code in GUI.vb to remove obsolete calls to
GetObjectProperty.
Merge pull request #32 from smackay/master

User Weather Control